Keyboard instrument and Piano accordion

Keyboard instrument noun - A musical instrument that is played by means of a keyboard.

Piano accordion and keyboard instrument are semantically related. In some cases you can replace phrase "Piano accordion" with "Keyboard instrument", this phrases are similar.

Piano accordion noun - A portable box-shaped free-reed instrument; the reeds are made to vibrate by air from the bellows controlled by the player.

Keyboard instrument and piano accordion are semantically related. You can use "Keyboard instrument" instead a noun phrase "Piano accordion".